I would say around the 1820. The Maclaren and Ferguson are the same apart from the yellow and white stripes, prior to 1820 the MacLaren was the Regent Tartan being woven by Wilsons for a number of years. Upon the Regent becomming King it was redundant as the Regent tartan but Wilsons apparently contunued to produce it. I would say it was snapped up by the MacLarens in the rush for tartans around that time. I would guess that the same is true for the Fergusons. Or was the Regent tartan a altered copy of a older Ferguson tartan. Good hunting on your quest